The present invention is concerned with immunomodulatory materials of natural origin. In particular, the present invention is concerned with peptides of invertebrate origin and pharmaceutical preparations comprising such peptides which are useful in the treatment of immune deficient conditions, infections and oncological diseases.
In the state of the art various pharmaceutical preparations of natural origin containing materials of animal, including insect, and plant tissues able to stimulate the immune system""s efficacy are known.
A process for obtaining cellular protein having anti-HIV activity from CD4-positive T cells or myeloid cells is disclosed in U.S. Pat. No. 5,480,782.
A topic formulation comprising a Ginkgo biloba extract exhibiting antibacterial and antiviral properties is disclosed in DE 43 34 600 A1.
WO 96/04005 discloses a pharmaceutical composition for stimulation of the immune response of an organism comprising as the active ingredient major histocompatibility complex antigens extracted from animal tissues, serum or cells. The tissues, cells or sera are chosen from goat, veal or pig liver and bovine red blood cells.
A pharmaceutical composition containing an extract of the plant Nigella sativa is disclosed in U.S. Pat. No. 5,482,711 for treating cancer, preventing the side effects of anticancer chemotherapy, and for increasing the immune functions in humans.
WO 81/03124 discloses a polypeptide fraction isolated from the mussel Mytilus edulis and used as antibiotic composition effective against various viruses, bacteria and protozoa.
Antibacterial peptides from honey bees and a process for their isolation, production and applications have been disclosed in EP 0 299 828 A1.
Antibacterial peptides isolated from the Coleopteran insects, Tenebdo molitor and Leptinotarsa decemlineata are disclosed in WO 90/14098.
Antibacterial protein isolated from the Lepidopteran insect, Hyalophora gloveri is disclosed in EP 0 856 519 A2.
Antimicrobial peptides structurally similar with arginine-containing fragments of lentivirus transmembrane proteins are disclosed in U.S. Pat. No. 5,714,577.
Antiviral and antimicrobial peptides isolated from porcine leucocytes are disclosed in U.S. Pat. No. 5,804,558.
Immunomodulatory peptides specifically binding major histocompatibility complex class II antigens and decreasing in that way a possibility of autoimmune disease are disclosed in U.S. Pat. No. 5,827,516.
EP 0 320 528 A1 discloses the use of hemocyanins and arylphorins isolated from various molluscs and arthropods including the insect Calliphora erythrocephala as stimulants the production of specific antibodies and the antitumor activity of antibody-dependent T-lymphocytes.
The preparations mentioned above and analogous natural pharmaceutical preparations enhance the recent arsenal of medicines suitable for treatment of immune deficient conditions, infections and oncological diseases. However, the pharmaceuticals which are available up to now do not cover existing demands in immunomodulatory medicines.
Therefore, it is an object of the present invention to provide a pharmaceutical preparation having immunomodulatory activity and in particular being useful for the treatment of immune deficient conditions, infections and oncological diseases.
It has now surprisingly been found that specific peptides exhibit the desired immunomodulatory activity.
Thus, the present invention relates to a peptide consisting of up to 30 amino acid residues and having the following general structural formula (1) (SEQ ID NO: 31):
X1-His-Gly-X2-His-Gly-Val-X3xe2x80x83xe2x80x83(1)
wherein
X1 is absent or represents at least one amino acid residue,
X2 is a peptide bound or represents at least one amino acid residue, and
X3 is absent or represents at least one amino acid residue,
or a pharmaceutically acceptable salt or ether thereof,
the peptide exhibiting immunomodulatory activity.
The present invention provides a new class of immunomodulatory peptides, designated xe2x80x9calloferonsxe2x80x9d herein, representative members of which were isolated from the blood of bacteria challenged larvae of an insect, blow fly Calliphora vicina R.-D. (Diptera, Calliphoridae).
The alloferons of the invention have been found to stimulate cytotoxic anticancer activity of animal (mouse) and human natural killer cells. Experimental data on the alloferons"" immunomodulatory activity show that they are able to stimulate the cytotoxic anticancer activity of human and mouse lymphocytes at extreme low concentrations. The minimum effective concentration was determined to be about 0.0005 nanogram/ml. The optimum concentration was found to be 0.05-0.5 nanogram/ml. Assuming the important role of natural cytotoxicity as effector mechanism of innate immunity (Trinchieri G., Advances in Immunology, 1989, vol. 47, 187-375; Brittenden J., Heys S. D., Ross J. and Eremin O., 1996, vol. 77, 1126-1243), alloferons may be useful as antiviral, antimicrobial and anticancer medicines of immunomodulatory mode of action.
Moreover, with regard to the stimulation of the anticancer activity of the cytotoxic lymphocytes, alloferons were found to induce intensive and prolonged interferon synthesis in experimental animals. Interferons are a group of key antiviral (alpha- and beta-interferons) and immunomodulatory (gamma-interferon) cytokins produced in the organism in response to viral infection and some other external stimuli. Elevation of interferons concentration in the blood helps to cure or mitigate a broad range of viral, oncological and autoimmune disorders. Injections of recombinant or natural interferons are successfully used in the immunotherapy of hepatitis C (Bekkering et al., J. Hepathology, 1998, 28, 6, p. 960-964), herpes (Cardamakis et al., Gynecol. Obstet. Invest., 1998, 46, 1, p.54-57), multiple myeloma (Zee et al., J. Clin. Oncol., 1998, 16, 8, p. 2834-2839), Hodgkin""s disease (Aviles et al., Leuk. Lymphoma, 1998, 30, 5-6, p. 651-656), myeloid leukemia (Gilbert H. S., Cancer, 1998, 83, 6, p.1205-13), multiple sclerosis (Durelli et al., Mult. Scler, 1995, 1, suppl. 1, p. 32-37), atopic dermatitis (Schneider et al., Ann. Allergy Asthma Immunol., 1998, 80, 3, p. 263-268), fungal infections (Kullberg, Eur. J. Clin. Microbiol. Infect. Dis., 1997, 16, p. 51-55) etc. Moreover exogenic interferons, inducers of endogenic interferon synthesis such as bropirimine, a phenylpyrimidinone analog, might be used to achieve similar therapeutic results (Akaza et al., Eur. Urol., 1998, 34, p. 107-110).
Experimental data show that alloferons effectively induce interferon synthesis and stimulate some immunological reactions (natural killers activity) in a manner similar to interferons. Therefore alloferons are believed to have similar therapeutic use compared to interferons and interferon inducers including but not limited to treatment of interferon-sensitive viral and cancer diseases. Direct confirmation of this hypothesis is obtained in experiments with virus infected mice. It is shown that alloferon administration significantly increase the survival rate in mice intrapulmonary infected with a lethal dose of human influenza virus A and B.
The chemical structure of alloferons has no similarity with interferons, other known cytokines and interferon inducers as well as any other materials of medical importance. The chemical structure of alloferons and the mode of biological activity are also quite different of those of arylphorin isolated from Calliphora and demonstrating immunologic and antitumor activity as it is disclosed in EP 0 320 528 A1. Alloferons preferably have a molecular mass close to 1200 Da and belong to the unique peptide family which has not been described so far. Calliphora arylphorin has a molecular mass of about 500 000 Da (Naumann U. and Scheller K. Biochem. Biophys. Res. Communications, 1991, 177, p. 963-971) and is proposed to be used as an adjuvant in the course of specific vaccination and specific stimulation of antibody-dependent T-lymphocytes antitumor activity as it is disclosed in EP 0 320 528 A1. No data concerning a possible effect of arylphorin on the natural killer cell activity and interferon synthesis are available up to now.
Alloferons are linear peptides having a unique amino acid sequence represented by the general formula as follows (SEQ ID NO: 31):
X1-His-Gly-X2-His-Gly-Val-X3
where:
X1 is absent or represents at least one amino acid residue
X2 is a peptide bond or represents at least one amino acid residue, and
X3 is absent or represents at least one amino acid residue.
The alloferons of the present invention have up to 30, preferably up to 20 and most preferable 5-13 amino acid residues.
Examples of alloferons of the present invention are summarized in Table 1.
Alloferons 1 and 2 are natural peptides isolated from the blood of bacteria challenged larvae of an insect, Calliphora vicina in the course of purposeful screening of cytokine-like materials able to stimulate cytotoxic activity of mammalian natural killer cells. Alloferons 3 and 4 are truncated forms of alloferon 1, which were chemically synthesized in order to determine possible biologically active modifications of the natural prototype molecule.
Comparative study of the effect of alloferon 1-4 on the cytotoxic activity of lymphocytes demonstrated that all of them are bioactive molecules. See Example 5. This makes possible to distinguish conservative (functionally important) and variable parts of the alloferon structure. Alloferons 5-20 are examples represented to show preferred modifications of variable fragments of the basic structure of alloferon.
A data base search did not reveal peptides of natural origin or bioactive synthetic peptides having close similarity to the alloferon structure. Therefore alloferons are believed to belong to a new family of bioactive peptides. Nevertheless, alloferons have, to certain extent, structural analogy with fragments of some functionally important proteins. For example, alloferon 1 has 63% identity with fragment 377-387 of the influenza virus B hemagglutinin precursor. Hemagglutinin is known to be a key membranotropic protein of the virus envelope responsible for the integration with the cell membrane of the host.
Alloferon 1 was used as a prototype molecule in the course of the development of the invention. Alloferon 1 is a linear peptide having a molecular mass of 1265 Da consisting of 13 amino acids. See Table 1. A comparison with alloferons 2-4 allows to determine functionally important elements of the structure of alloferon, which are necessary for its efficacy as a stimulant of NK cell""s cytotoxicity and, other activities, and to predict possible structural modifications, which do not change the biological activity of the peptide.
Comparison of alloferon 1 with the structure of alloferons 2-4 shows that the presence of the fragment Ser-Gly-His-Gly-Gln-His-Gly-Val (SEQ ID NO: 32) is sufficient to conserve the biological activity as since all the peptides exhibit similar activities in NK cell cytotoxicity test. Therefore, this fragment or a part of the fragment represents the core conservative structure in alloferon sequences. Positions 1-3 in the alloferon 1 molecule can be missing or can be replaced by one or more amino acids.
Furthermore, a comparison with the homologous fragment of the influenza virus hemagglutinin reveals that positions 4 and 5, represented in the alloferon 1 sequence by amino acids serin (Ser) and glycin (Gly), can be replaced by some other amino acid preferably chosen from the group of aliphatic, aromatic or heterocyclic amino acids. For instance, serin can be replaced by threonin (Thr) and glycin by serin.
Thus, the available data reveals that the first five amino acids in the alloferon 1 sequence are a variable fragment which can be absent or contain at least one amino acid. Therefore, this fragment is marked in the alloferon structural formula (1) as X1. Advantageously, X1 is selected from the group consisting of nothing, His-Gly-Val-Ser-Gly-(SEQ ID NO: 22), Gly-Val-Ser-Gly-(SEQ ID NO: 23), Val-Ser-Gly-, Ser-Gly-, Pro-Ser-Leu-Thr-Gly-(SEQ ID NO: 24), Phe-Ile-Val-Ser-Ala-(SEQ ID NO: 25), Thr-, Leu-Ala-Ser-Leu-(SEQ lID NO: 26), Cys-Val-Val-Thr-Gly-(SEQ ID NO: 27), Ile-Ser-Gly-, Cys-Gly-, Ile-Val-Ala-Arg-Ile-(SEQ ID NO: 28), Phe-Gly-, His-Gly-Asp-Ser-Gly-(SEQ ID NO: 29), Ser-Gly- and Tyr-Ala-Met-Ser-Gly-(SEQ ID NO: 30).
Similarly, positions 14-15 in the alloferon 1 molecule can be missing or can be replaced by a sequence of one or more amino acids. Therefore, this fragment is marked in the alloferon structural formula (1) as X3. Advantageously, X3 is selected from the group consisting of nothing , -His-Gly, -His, -Tyr-Asp, -Phe-Val, -Pro, -Gln-His-Gly, -Leu-Ala, -Asp, -Pro-Leu, -Met and -Phe-Ile.
Moreover, comparison of alloferon and the corresponding hemagglutinin fragment reveals that position 9, occupied in the alloferon molecule by glutamin, is also variable and glutamin can be replaced by some other amino acid, for example, by alanin. Consequently, position 9 of the alloferon structural formula (1) is marked as X2,which can be a peptide bond linking Gly and His or contain not less then 1 amino acid, preferably 0-3 amino acids, more preferably 0-2 amino acids and most preferable 1 amino acid, in particular -Gln-.
Advantageously, X2 is selected from the group consisting of a peptide bond, -Gln-, -Phe-, -Asp-, -Ser-, -Asn-, -Ala-, -Gln-Asn-, -Ala-Val- and -Ser-Asp-Gly-.
Incorporation of the alloferon sequence into a larger molecule such as a carrier protein without significant alteration of the biological activity of the alloferon is also possible. Thus, the present invention also relates to chemical compounds such as peptides or proteins comprising an amino acid sequence having the above general formula (1), provided that the peptide or protein is not naturally occurring, and in particular not the influenza virus B precursor.
Complex immunological, pharmacological and toxicological studies summarized in the examples below demonstrate a range of useful properties of alloferons. The obtained data show that alloferon is a new cytokine-like peptide. The mode of action of alloferon comprises stimulation of nonself or aberrant self recognition of cells and lysis by the cytotoxic lymphocytes as well as induction of interferon synthesis. Therefore, alloferon is useful as immunomodulatory medicine to correct a deficiency in the production of interferons and activity of natural killer cells, treatment of viral, oncological and other diseases dependent on the said deficiency. Alloferon is practically nontoxic, has no teratogenic, embryotoxic or mutagenic properties as it is shown in advanced preclinical studies.
The experimentally established properties of alloferon 1 are summarized in Table 2.
The pharmacological activity spectrum, in general, corresponds to known properties of interferon-alpha concerning the influence on the cytotoxic activity of natural killer cells and antiviral resistance. In that aspect, alloferon can be characterized as interferon-alpha functional analog. The mode of action of alloferon, regarding in vitro stimulation of NK cells cytotoxic activity, is observed at very low concentrationsxe2x80x94about 1 picogram/ml (10xe2x88x929 g/ml). In that aspect alloferon is as active or more active as endogenous cytokines, interferons and interleukins.
Moreover, alloferon is able to induce, alone or in cooperation with interleukin 12, the synthesis of endogenic interferons, including interferon-gamma. Therefore, alloferon can be attributed to the group of interferon inducers.
Preclinical studies of the in vivo activity of alloferon show that it has potent antiviral activity when tested using as a model mice infected by human influenza virus. In this model wild type males were infected intranasally by a suspension of the human influenza virus and alloferon 1 was injected intraperitoneally one day before infection and then 1, 2, 4, 6 and 8 days after. Alloferon effectively protected mice from pulmonary lesions and death. Thus, alloferons are useful in the preparation of a pharmaceutical preparation for the treatment or prevention of viral infections.
Neither an acute nor a chronic toxicity of alloferon 1 was found in the course of in vivo and in vitro studies.
It is understood that the pharmaceutical preparations of the present invention may also comprise conventional additives like excipients or carriers. The preparations may be administered to the patient by intranasal, enteral, such as oral or rectal, and parenteral, such as intraperitoneal, intramuscular, intravenous or subcutaneous route. The preparations may be administered in dosage forms such as intranasal dropping solutions, sprays, liposomes, capsules, tablets and suppositories. For parenteral use the pharmaceutically active components are preferably in the form of an injectable solution.
Thus, alloferons are useful in the treatment or prophylaxis of various infectious or oncological diseases where improvement of innate immunity, including interferon system and natural cell mediated cytotoxicity, can have therapeutic significance. The examples of conditions under which alloferons application is prospective comprise influenza virus and other respiratory viral infections, viral hepatitis, AIDS and AIDS relevant secondary infections and oncological conditions, acute and chronic leukemia and other cancers where interferon treatment efficacy is proved, fungal systemic infections sensitive to the interferon treatment etc.
In spite of a certain similarity in biological activity (NK cell cytotoxic activity stimulation, indirect antiviral activity), alloferons differ very much of interferons in terms of structure and mode of action. Thus, interferons are glycoproteins with molecular mass ranging from 17 000 to 80 000 daltons. Glycosilation of amino acid chain is a necessary condition of interferon functional activity as well as their tissue and species specificity. Alloferon is a preferably nonglycosilated oligopeptide having molecular mass of preferably about 1265 Da, 13-60 times less then interferons molecular masses. The amino acid sequence of alloferon has no similarity with any fragment of interferon sequences. There are essential differences between alloferons and interferons in functional aspect as well. Thus, alloferon induces the production of endogenic interferons and promotes in this way a cascade of defense responses mediated by interferons. Exogenic interferon application may rather suppress endogenic interferon synthesis by means of negative feedback mechanism.
The peptides of the present invention can be isolated from natural sources or synthesized by known methods. The peptides of this invention can also be produced by recombinant DNA techniques. Thus, the invention comprises cultivating a cell host previously transformed with a suitable vector containing a DNA sequence, e.g. a cDNA encoding a peptide sequence including any of the peptides of this invention, said DNA sequence being placed under the control of a promoter and followed by termination signals recognized by the cell host machinery such as to authorize the expression said DNA sequence of said peptide sequence, and recovering the peptide sought from the expression of products of the cell culture. Advantageous host cells belong to Lactobacillus strains, E. coli, Agrobacterium or Bacillus strains. Alternatively the peptides can be easily produced by well known chemical synthesis.
The invention is further illustrated by the following examples: